We propose to acquire an 18-color, 5-laser BD Biosciences FACSAria-II cell sorter, with bio- containment hood and novel CellEvator acoustic wave powered sample mixer technology. This instrument will expand the availability of researchers to access cell sorting capabilities in the URMC Flow Cytometry Core facility. Since the acquisition of our current FACSAria-I, in April of 2008 and concurrent retirement of an older generation cell sorter, our usage has gone from an average of 600 hours/year (pre April, 2008), to over 1200 hours in one year. Our anticipated growth in usage will top over 1500 hours by the end of August, 2009, with many of our sorts running from 12 noon till 8 pm. We are also in a position that stresses our ability to sort opportunistic clinical samples from precious patient samples. The addition of this new sorter will alleviate this concern, allowing further advances in our translational research programs. The FCC, in close collaboration with the Rochester Human Immunology Center (RHIC), has been very successful developing informative analytical flow panels in the mid- (8-12 color) and high end (>12 color) area, which has generated increasingly important, more relevant, and comprehensive data in the study of the role of B cells in autoimmune diseases, measures to improve treatment of lymphoma, studies of the hematopoietic microenvironment, B and T cell immune responses to pathogens including nematodes and influenza, and normal maturation of the hematopoietic stem cell in early developmental models among other efforts. With the ability to identify and sub-set complex populations, comes the need to isolate and study these sub-sets. Thus the proposed instrument will augment and extend our abilities from just identification and enumeration of these cells, to the ability to isolate and study in great detail with the host of tools available for genomic, proteomic and biochemical characterization of normal and diseased states. Systematic advances in electronics, lasers, and optics have made current instruments capable of detection of up to 18 simultaneous fluorescent parameters from a single cell. This makes the detection of more fluorescent markers by high-end instrumentation an absolute necessity in order to capture every nuance of cell activity to reveal the subtlest differences between normal and diseased cells - most especially for clinical-translational research on rare patient samples.